Professor Sir Nevill Francis Mott Should Be on the Application of Wave CH, KB, Scd, FRS, Chevalier Ordre Nat

84 PROFILE head of theoretical physics at the Cavendish, Ralph Fowler, he set about finding his own problem which he decided Professor Sir Nevill Francis Mott should be on the application of wave CH, KB, ScD, FRS, Chevalier Ordre Nat. du Merite, Nobel Laureate in Physics mechanics to the scattering of charged particles - an active area of experimental investigation led by Ernest Rutherford. This work was published in the Proceedings of the Royal Society. One year after he graduated with first- in numerous countries - via handwritten class honours in 1928, Fowler arranged a letters most of which contained gems of grant to enable him to spend a year ideas that were treasured by their abroad, which he divided between visits to recipients. Unlike most of us he didn’t Copenhagen and Gottingen. At Copen have a cluttered desk with a massive pile in hagen he discussed with Niels Bohr the the in-tray; he worked in “real time”, startling prediction of Dirac in Cambridge writing first drafts of papers as ideas that the electron carried a spin, and began occurred to him and answering letters, work on a related problem. He clearly responding to requests for information, found it exciting to be in the company of and writing referee’s reports, references Bohr and other famous scientists of the era etc., often by return post. His mind was - for example, Pauli, Gamow, Heisenberg his principal filing cabinet. In these ways and Hartree, who visited Bohr’s famous he drew together ideas and people from institute. Before moving on to Gottingen, different disciplines in a unique manner. he returned for a few months to Cam bridge where he solved an important Born 30 September 1905, died 8 August 1996 problem relating to the scattering of alpha Early years particles. Chadwick, Rutherford’s second The death of Sir Nevill Mott at age 90 It was natural that Mott should take an in command, was clearly impressed and brought to a close the illustrious “life in early interest in physics. His mother and took Mott along to see Rutherford who science” of a man who stood academically, father both worked at the Cavendish exclaimed “If you think of anything else as well as literally, head and shoulders Laboratory at Cambridge University with like this, come and tell me.” This was above his contemporaries, many of whom J.J. Thomson, a few years after J.J.’s praise indeed and he later recalled it was were awed and inspired by his remarkable identification of cathode rays with on that day when he gained complete powers of intuition, his penetrating insight “corpuscles” (electrons) in 1897. In his confidence in his ability to make a career and his versatile creativity. autobiography “A Life in Science” he in theoretical physics. The staggeringly long length of his records that quite early in his life his While in Gottingen, where he had scientific career - his first paper was parents communicated to him the hoped to work with Max Born - an published in 1927 during the early days of excitement and importance of physics. opportunity that did not materialise owing quantum theory and his last on high- His mother taught him at home until he to Born being in poor health - Mott temperature superconductivity in 1996, was ten when he became a weekly boarder received an offer of a lectureship at four months after his death - must be at a small preparatory school near Manchester University under W.L. Bragg, unprecedented, and the range of his Stafford. Before he left that school at age which he accepted. A course of lectures he contributions to physics possibly 13 he was, according to his own words, gave there on wave mechanics led to his unequalled. He was the author of at least advanced in algebra and Latin and had first book “An Outline of Wave Mechanics” fifteen books and over three hundred been introduced to calculus. He spent the written at age 25. It was at Manchester scientific papers, covering a range of next five years as a boarder at Bristol’s where his interest turned to the properties topics as diverse as wave mechanics, Clifton College, where a gifted teacher, H. of materials, stimulated no doubt by the nuclear physics, the properties of metals, C. Beaven, instilled in him the beauty of power of the new technique of X-ray ionic crystals, semiconductors and glasses, mathematics. Later he recalled the crystallography to determine the structure and the nature of superconductivity - an excitement he felt when, at about age 16, of solids - a method which earned W.L. impressive list but, even so, one which he realised why any number raised to the Bragg (later Sir Lawrence and Cavendish does not convey or do justice to the range power nought equalled unity! In Professor of Experimental Physics) the of his activities. December 1923 he was awarded a major Nobel prize for physics, jointly with his Nevill Mott was a theoretical physicist scholarship by St John’s College, father W.H. Bragg. - a label far too narrow and restrictive to Cambridge, where he read for the An invitation to return to Cambridge describe his output and methods of mathematical tripos. came in 1930 and Mott accepted a working. His principal posts were at In spite of his mathematical ability, fellowship at Gonville and Caius College. Bristol and Cambridge but he was the Mott was never tempted to be a pure Now married, he found that theoretical “father” of a much larger community, mathematician; physics was his main physicists were rather more respected communicating (without the benefit of e- interest. His first research was undertaken than when he had first entered the mail) with hundreds of scientists, when he was an undergraduate. In the Cavendish. Nevertheless, the prime Europhysics News 28 28 1997 News Europhysics theoreticians and experimentalists alike, absence of any real suggestions from the interest there was still in atomic physics PROFILE 85 and 1932 was the Annus Mirabilis of the Europe, particularly in Germany, by the many recall the excitement at these Cavendish, when the neutron was application of quantum mechanics to the meetings. Numerous problems and discovered, the atom split and the positron understanding of the properties of metals puzzling properties of metals were solved (positive electron), predicted by Dirac, and of the difference between metals and at Bristol during those heady days - was first observed. Stimulated by this semiconductors. The work of Sommer- advancing the subject and, at the same extraordinary atmosphere and a field, Bloch, Peierls and Bethe was time, providing much of benefit to suggestion by Fowler that he write a book especially successful and Mott set about industrial metallurgists. on atomic collisions, Mott collaborated continuing this tradition. He found an In those six pre-war years at Bristol, with Harrie Massey to produce a classic enthusiastic supporter in Harry Jones, a Mott did not confine his attention to tome “The Theory of Atomic Collisions”, former research student of Fowler’s, and understanding the physics of metals. He which ran to several editions. together they wrote a famous textbook began his first work on semiconductors, a “Theory of the Properties of Metals and field with which he was to remain attached Bristol Alloys”. Strange as it may now seem to the for many more decades - in fact, well into In 1933, Mott accepted his first Chair, hundreds of solid-state physicists who his retirement. The initial stimulus came that of Professor of Theoretical Physics at learned their basic quantum mechanics of from Ronald Gurney who had arrived Bristol University. For six years up to the solids from this work, the book was not from Manchester and who, like Mott, had outbreak of the Second World War, he that well received by other theorists, being a remarkable talent for visualizing solids played a significant role in establishing criticised for lack of rigour. What in fact in terms of their constituent atoms and Bristol as one of the foremost centres for we see in this book is mathematics applied electron waves, without the need for solid-state physics. His philosophy, which to the direct interpretation of experi detailed mathematics. Together they he never abandoned during the remainder mental data, interspersed with bold wrote another “Mott and X” book (where of his life, was to have theoreticians and initiative ideas which leapfrog the formal in this case X was Gurney) titled experimentalists working closely together. development when the rigorous mathe “Electronic Processes in Ionic Crystals”. Together they laid the foundation of the field of colour centres in alkali halides by providing a description of the defects involved in terms of negative ion vacancies. They also worked out the physics behind the photographic process - why light falling on a grain of silver bromide was able to produce a speck of silver - the latent image. In 1940 Mott was awarded the Harker and Driffield medal from the Royal Photographic Society for this work. Four years earlier, at the age of 31, he had been elected a Fellow of The Royal Society. Mott’s personal qualities and human- itarianism were evident after the German occupation of Sudetenland, when there was a movement to rescue children of Physics Department, University of Bristol, 1935 Jewish descent from Czechoslovakia. He Front row, reading left to right looking at the photograph: W. Sucksmlth, H.W.B. Skinner, G.l. Harper, L.C. Jackson, N.F. and his wife, Ruth, with help from his Mott, A.M. Tyndall, S.H. Piper, I. Williams, H.H. Potter, W. Heitler. sister, Joan, housed two young refugees, Second row, reading left to right: ...Huntley, S.E.

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